Well the proportions and stuff are really good. I think most of the details are there.
It's hard to see stuff though. Halo is also known for it's high contrast. So if the lights were brighter and maybe the shadows darker, it might look a lot better. It would also look less flat that way.
I like how you put the stripes in. I think that's the first time for tb.
Well I'm viewing this from a dim small screen, so Im probably missing out on a lot of this set >_>
it's definitely one of the better halo sets, primarily for it's accuracy as far as I could tell.
Screenshots are pretty necessary so it's great that you used 50!